Non-empty list with null elements returned from Hibernate query

Question

Hi,

I'm new to hibernate so not sure if this is an expected behaviour, anyway:

Session session = (Session)entityManager.getDelegate();
Criteria criteria = session.createCriteria(myRequest.class);
criteria.add(Restrictions.eq("username", username));
criteria.setProjection(Projections.max("accesscount"));
List<myRequest> results = criteria.list();

The returned results is a non-empty list with a single null element.

I can't think of any reason why it should behave this way, any idea if this is the expected behaviour or have I done something wrong?

System is on hibernate/Syabse.

Thanks.

Answer 1

It's only surprising if there was a user with that username who had a non-null value n the accesscount column. Your return type leads one to believe that you were trying to get the instance of myRequest that has the max accesscount? this is not what that query does. The query is the equivalent of

select max(m.accesscount) from myRequest m where m.username = :username

It's just (trying to) return a number, not a myRequest.